This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The long-range goals of the this research program are (1) To learn how the mechanistic ideas of organic chemistry can be extended to deal with the making and breaking of covalent bonds throughout the periodic table. (2) To use the knowledge gained through study of reactive intermediates and reaction mechanisms to make new molecules, new types of bonds, and new materials. The approach we have taken has been to study the reactions of atoms, molecules and ions small enough to be well-characterized by spectroscopic measurements and amenable to theoretical as well as to experimental treatment. We have examined the chemistry of highly reactive short-lived species containing electron-deficient group XIV atoms, including carbenes, carbo-cations CC and CH, silyl radicals RSi., silylenes RSi:, silenes RSi=CR, silicon-centered cations SiH, germylenes, RGe:, germenes RGe=CR, phosphinidenes R-P, and free atoms C, Si, and Ge.